JP2982090B2 - Method and apparatus for measuring torque in valve actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring torque in a valve actuator for opening and closing a valve device used in a power plant or a chemical plant, and a device therefor.

[0002]

2. Description of the Related Art In power plants and plants, a large number of relatively large valve devices are used, and valve actuators for driving those valve devices also use large output torque. The valve actuator has a built-in torque limiting means. Particularly in a high-output valve actuator, the output torque is limited to prevent damage to the valve device due to excessive driving.

[Problems to be solved by the invention]

Conventionally, even when an abnormality or failure occurs in the torque limit means of the valve actuator, or when a test for confirming the output torque is performed by maintenance and inspection, the valve actuator is detached from the valve device and the factory is removed. The test was carried out by returning the test instrument to a valve actuator or to a site where the valve actuator was installed.

However, in a valve device used in a complicated control system such as a power plant or a chemical plant, the inability to use one valve device affects the entire control system and causes a system down or the like. become. Therefore, in order to send the valve actuator back to the factory, it is necessary to take measures such as preparing an alternative or forming a bypass of another route in the control system of the valve device.

Further, valve actuators used in valve devices of nuclear power plants and the like cannot be removed and taken out of the power plant, and some of them are not easy to approach for maintenance and inspection. is not. An object of the present invention is to provide a method and an apparatus for always obtaining an accurate output torque without removing a valve actuator.

[0006]

According to the torque measuring method of the present invention, a load resistance applied to a worm wheel is converted into an axial thrust of the worm, and a spring resisting the thrust is provided between the worm and the fixed base. When a worm generates a thrust in one of the axial directions in a valve actuator that generates a required torque on the worm wheel by intervening, the thrust is electrically detected and the torque value is set to the required value. In calculating and detecting the thrust generated in the worm, a comparison between the position of the worm in the process from the time of generation of the thrust to the time when the maximum thrust is obtained and the thrust corresponding to the position of the worm is obtained, and the amount of deflection of the spring is calculated. When the spring characteristic of the repulsive force is detected, and when the worm generates a thrust in another direction, the moving amount of the worm is detected, and the worm in the spring characteristic is detected. From the amount of movement of the over arm, it is characterized in that to calculate the output torque to a required seeking repulsive force of the spring.

Further, a torque measuring device according to the present invention includes a worm wheel connected to a load, and a worm wheel that meshes with the worm wheel and that is connected to a drive shaft so as to be movable in an axial direction and non-rotatable in a rotational direction. A worm, a spring for generating torque interposed between one end of the worm and a required fixed portion, and a spring interposed between the fixed portion side and the fixed base portion of the spring, and a spring formed between the fixed portion side of the spring and the fixed base portion. A pressure detection sensor for detecting a pressing force between the pressure sensor, a position detection sensor for detecting the position information of the worm in association with the worm as required, and an output signal of the pressure detection sensor and the position detection sensor, and a pressure detection sensor. Is pressurized, the pressure is converted into a torque value and output, and the pressure detection sensor updates the spring characteristics by detecting the spring characteristics of the spring deflection versus the repulsion force during the pressurized period. And The force sensor non pressurized, is characterized in that a microcomputer controller for calculating a torque value at that time from the spring characteristic that is updated again based on the amount of movement of the worm.

[0008]

When the thrust is generated in one of the axial directions of the worm and pressure is generated at the fixed base of the torque generating spring, the worm movement detection means and the pressure detection means determine the worm movement amount. The pressure is detected, and at that time, the output torque is converted from the pressure and calculated, and the spring characteristic of the spring is calculated from the movement amount of the worm and the pressure. Based on the characteristic, the magnitude of the thrust generated in the worm is obtained based on the worm movement detected by the worm movement detecting means, and the output torque is calculated.

[0009]

FIG. 1 is a cross-sectional view of a main part of an embodiment of the present invention. The valve actuator (1) has an input shaft (4) connected to an output shaft (3) of a drive motor (2), and a worm gear (5) is connected to the input shaft (4). The worm (6) of the worm gear (5) is fitted around a spline shaft (4a) provided on the input shaft (4), is movable in the axial direction, and cannot rotate in the rotation direction. Are combined.

The worm wheel (7) meshing with the worm (6) in the worm gear (5) is a worm wheel.
A nut member (8) that is non-rotatably coupled to the center of (7) is provided, and the nut member (8) is screwed to a screw portion (9a) of the output shaft (9). Output shaft in valve actuator (1)
(9) generally corresponds to the stem axis of the gate valve, and a screw (9a) screwed into the nut member (8) is engraved at the upper end thereof, and a valve device (not shown) is formed at the lower end thereof. The valve body is coupled and slidable in the vertical axis direction and cannot rotate in the rotation direction.

Output shaft (9) serving as a stem shaft in the valve device
When the valve is closed, the valve reaches its lowest end when the valve is fully closed, so that the output shaft (9) cannot be lowered any more and the load resistance increases rapidly.

Similarly, when the valve is fully opened during the valve opening operation, the valve reaches the uppermost end, abuts against a required stopper, making it impossible to further raise the valve, and the load resistance rapidly increases. When the output shaft (9) cannot move when the valve is fully closed or the valve is fully opened, the worm (6)
When (7) cannot rotate, it receives a screw feed action and generates a thrust in the axial direction.

The right end of the worm (6) opposite to the drive motor (2) is extended in the axial direction and is provided with a radially enlarged step (11) at the left end via a radial thrust bearing (10). The sliding shaft (12) is connected to the inner cavity (11a) of the enlarged diameter step (11).

The inner ring (10a) of the radial thrust bearing (10)
The nut (13) on the step (6b) of the extension (6a) of the worm (6)
The outer ring (10b) is also fixed to the bore (11) of the sliding shaft (12).
The worm (6) and the sliding shaft (12) are rotatable around the axis and move in the axial direction by being fitted into the step (11b) of (a) and being locked by the retaining ring (14). It is linked to impossible.

The outer periphery of the enlarged diameter step (11) of the sliding shaft (12) is slidably fitted in a shaft hole (16) provided in a casing (15). A multi-stage disc spring (18) is fitted on the diameter-reducing shaft (17) extending rightward of the sliding shaft (12), and the diameter-expanding step (11) of the disc spring (18) is fitted.
On the left end of the side, a washer with a diameter larger than the outer diameter of the step (11)
(19) has a washer (1)
A washer (20) of the same diameter as or slightly smaller than that of (9) is abutted, and the right side of the washer (20) is pressed with a nut (21) to compress the disc spring (18) to the required initial pressure. Have been. The washers (19) and (20) are fitted slidably in the axial direction with respect to the reduced diameter shaft (17).

The washer (1) on the side of the enlarged diameter step (11) of the sliding shaft (12).
9) is in contact with the enlarged diameter step (22) provided at the right end of the shaft hole (16) into which the enlarged diameter step (11) is fitted, and cannot move to the left. The right washer (20) is on the right side near its outer periphery,
The open end (23a) of the bottomed cylinder (23) is in contact.

At the center of the bottom (24) of the bottomed cylinder (23), a hollow shaft (25) projecting rightward is provided, and the right end of the hollow shaft (25) is
It is screwed into the center of the pressure sensor (26), and is narrowed down by a nut (27) and fixed to the pressure sensor (26).

The pressure sensing sensor (26) is generally called a load cell or the like, and measures a very small strain or displacement caused by pressurization, converts the amount of strain or displacement into a pressing force or a load, and outputs an electric force. Is measured.

The pressure sensor (26) has a built-in strain gauge, semiconductor pressure sensor, and the like for electrically detecting strain and displacement. The pressure sensor (26) has a shaft hole (16)
The outer peripheral portion is fixed to the end of the extension cylinder (28) fixed to the casing (15) forming the above.

A differential transformer type position detecting sensor (30) is provided at the center of a pressing plate (29) for pressing the pressure detecting sensor (26) from the right side. The movable part (movable iron core) (31) is provided with a reduced diameter axis (1
At the right end of 7), it is fixed through the hollow shaft (25).

When the worm (6) receives a thrust to the right when the valve actuator (1) reaches the fully opened position during operation of the valve actuator (1), the sliding shaft (12) pushes the washer (19) while pressing the washer (19). The spring (18) is compressed, and the reduced diameter shaft (17) slides through the inner hole of the washer (20) and projects rightward.

The amount of movement of the sliding shaft (12) at this time is accurately measured by the amount of movement of the movable part (31) of the position detection sensor (30). The pressure of the disc spring (18) is transmitted from the washer (20) to the pressure sensor (26) via the bottomed cylinder (23), and the compression force of the disc spring (18) is measured. The above-mentioned disc spring
The repulsion force compressed in (18) pushes the worm (6) back to the left, and generates a torque corresponding to the repulsion force on the worm wheel (7).

On the other hand, when the valve reaches the fully closed position and the worm (6) receives a thrust to the left during operation of the valve actuator (1), the sliding shaft (12) is pressed to the right by the nut (21). Press the washer (20) and move it to the left.

At this time, the washer (19) on the left side is
2), the reduced diameter shaft (17) slides to the left through the inner hole of the washer (19) and slides the disc spring (1).
8) Compress.

The amount of movement of the sliding shaft (12) is accurately measured by the position detection sensor (30). Since the sliding shaft (12) and the worm (6) are integrally connected in the axial direction, the moving amount of the sliding shaft (12) and the moving amount of the worm (6) are the same. . When moving the sliding shaft (12) to the left,
No load is applied to the pressure sensor (26).

However, in the present invention, the compression force of the disc spring (18) when the worm (6) moves to the left, that is, the generated torque, can be known as follows. FIG. 2 is an electric circuit for achieving the above object.

(32) and (33) are analog / digital converters, (34) is a microcomputer control unit, (35) is a display, (36) is a communication interface, and (37) is Central monitoring master station, (38) is an IC card, (39) is a ROM (read only memory) of a microcomputer control unit (34), and (40) is a microcomputer control unit (34).
(Random access memory).

The microcomputer control unit (34) includes an output signal (L) of the position detection sensor (30) and a pressure sensing sensor (26).
After the output signal (F) is converted by the analog / digital converters (32) and (33), respectively, and inputted, the disc spring shown in FIG.
The bending characteristic of (18) is detected.

The initial value (A) of the bending characteristic is set so as to give a large amount of bending, that is, the rightward movement of the worm (6) in advance at the time of shipment from a factory or during an installation test.
It is preferable to obtain the characteristics of the movement range of (6).

The initial value (A) of the deflection characteristic is determined by the ROM (3
Recorded in 9). The initial value (A) of the flexure characteristic is determined each time the valve actuator (1) starts operating and the worm (6) moves to the right and the output (F) of the pressure sensor (26) is obtained. If there is a change based on the movement amount data of (6), that is, the output (L) of the position detection sensor (30), the data is updated, and the updated bending characteristic update value (B) is updated.
Is stored in the RAM (40) backed up by the battery (41).

The updated value (B) is recorded on an IC card (38) containing a battery (42), displayed on a display (35), or transmitted via a communication interface (36). It can be sent to the central monitoring master station (37).

When the worm (6) moves to the left,
As shown in FIG. 4, the pressure (F) is obtained from the moving amount (L) to the left based on the updated value (B) recorded in the RAM (40) or the IC card (38), and the output torque is obtained. Is calculated.

Thus, an accurate output torque can be always obtained in any moving direction of the worm (6) based on the accurate pressure calibrated by the pressure sensor (26).

[0034]

The present invention has the following effects. (a) Since the output torque of the valve actuator is obtained using the pressure value measured by the direct pressure sensor or the value obtained from the latest deflection characteristic data calibrated with the pressure value, highly reliable opening and closing of the valve Control can be performed. (b) From the difference between the initial value of the spring deflection characteristic data and the updated calibration value, fatigue and wear of the valve actuator mechanism can be detected, and failures and failures can be detected at an early stage. System down of a valve control system of a power plant or the like can be prevented. (c) Since the deflection characteristics of the spring are electrically detected, the latest data and history data can be easily moved and communicated by the IC card and the communication means, and the maintenance and inspection time can be easily estimated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a valve actuator showing one embodiment of the present invention.

FIG. 2 is an electric block diagram showing an embodiment for performing electric signal processing of the present invention.

FIG. 3 is a characteristic diagram when recording a deflection characteristic of a spring in a ROM or a RAM.

FIG. 4 is a characteristic diagram when a torque is obtained based on a movement amount of a worm from a deflection characteristic of a spring recorded in advance.

[Explanation of symbols]

(1) Valve actuator (2) Drive motor (3) Output shaft (4) Input shaft (4a) Spline shaft (5) Worm gear (6) Worm (6a) Extension (6b) Step (7) Worm wheel (8 ) Nut member (9) Output shaft (9a) Screw (10) Radial thrust bearing (10a) Inner ring (10b) Outer ring (11) Expanded step (11a) Lumen (11a) Lumen (11b) Step (12) Sliding shaft (13) Nut (14) Retaining ring (15) Casing (16) Shaft bore (17) Reduced diameter shaft (18) Disc spring (19) (20) Washer (21) Nut (22 ) Expanding step (23) Bottomed cylinder (24) Open end (25) Hollow shaft (26) Pressure sensor (27) Nut (28) Extension cylinder (29) Holding plate (30) Position detection sensor (31) Moving parts (moving iron core) (32) (33) Analog / digital converter (34) Microcomputer control part (35) Display (36) Communication interface (37) Central monitoring master station (38) IC Card (39) ROM (40) RAM (41) (42) Battery (A) Initial value (B) Update value (L) (F) Output signal

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01L 3/14 G01L 25/00 F16K 31/04

Claims (2)

(57) [Claims] 1. A load resistance applied to a worm wheel,
A valve actuator that converts the thrust into the axial direction of the worm, and interposes a spring against the thrust between the worm and the fixed base to generate a required torque on the worm wheel. When a thrust is generated in one of them, the thrust is electrically detected, the torque value is calculated as required, and the process from when the thrust is generated until the maximum thrust is obtained when detecting the thrust generated in the worm The worm position is compared with the thrust corresponding to the worm position, and the amount of deflection of the spring versus the spring characteristic of the repulsive force is detected.When the worm generates thrust in the other direction, the amount of movement of the worm And detecting the required output torque by calculating the repulsive force of the spring from the movement amount of the worm in the spring characteristic. Torque measurement method in the actuator. 2. A worm connected to a load, a worm connected to a drive shaft, the worm being engaged with the worm wheel and being movable in an axial direction but not rotatable in a rotational direction. A torque generating spring interposed between the end and the required fixed portion, and a pressure interposed between the fixed portion side of the spring and the fixed base to detect a pressing force between the fixed portion side of the spring and the fixed base. A detection sensor, a position detection sensor that detects the position information of the worm in association with the worm as required, and an output signal of the pressure detection sensor and the position detection sensor are input, and when the pressure detection sensor is pressurized, The pressure is converted into a torque value and output, and the spring characteristics of the spring deflection versus the repulsion force during the period when the pressure detection sensor is pressurized are detected, the spring characteristics are updated, and the pressure sensor is not pressurized. Sometimes w Torque measuring device in the valve actuator, characterized in that a microcomputer controller for calculating a torque value at that time from the spring characteristic that is updated again based on the amount of movement of the arm.